I guess you could get all semantic about bb heights, head angles and frame weights ('race' frames being lower, slacker and lighter), but a solid ride is a solid ride. The one thing that would be the biggest difference is horizontal or vertical dropouts. DJ frames will be horizontal for running single speed, race frames vertical meant to be run with gears. But even that's not set in stone. If you want a dirtjumper and that's one you can get a deal on that appeals to you, hit it.